The present invention relates to a travelator, moving ramp or escalator. In prior art, a travelator, moving ramp or escalator is known which comprises a power means and a conveyor having an end driven by the power means and a non-driven end. The conveyor comprises a first drive element and a second drive element, which are disposed at a distance from each other and parallel to each other, each being implemented as an endless loop. The drive elements are usually link chains or toothed belts.
A number of conveyor platforms, such as pallets, are arranged one after the other and secured to the first and the second drive elements. At the driven end of the conveyor, the first drive element is passed over a first driving pulley rotated by the power means and at the non-driven end over a first diverting pulley. The second drive element is passed at the driven end of the conveyor over a second driving pulley rotated by the power means and over a second diverting pulley at the non-driven end. Arranged at the driven end are synchronizing means for mutual synchronization of the first driving pulley and the second driving pulley.
The elongations of the drive elements at the non-driven end of the conveyor may be different.
In conventional prior-art travelators, moving ramps and escalators, the transport length of the conveyor is reasonably short and the link chains usually employed as drive elements are of a very heavy design. For example, the effective diameter of the driving pulley may be on the order of 60 cm and the chain pitch 130-150 mm. The difference of elongation of the link chains on opposite sides does not become very large and no problem arises.
Today, however, there is a need for travelators, moving ramps and/or escalators in which the transport distances are very long and in which the distance between the driving and diverting pulleys of the drive elements are consequently also very long. For example, in very long travelators, the distance between the driving and diverting pulleys is long, e.g. on the order of 100 meters.
Further, there has arisen a need for travelators, moving ramps and escalators of low-construction height designed to be mounted directly on a fixed base, such as a floor, without any special pits formed in the fixed structure, such as the floor of a building, for embedded mounting of the frame and machinery of the travelator. In the frame structure of a travelator, moving ramp or escalator mounted on a fixed base there is very little space for the drive machine of the conveyor, and therefore the diameter of the driving and diverting pulleys can not be very large and correspondingly the drive elements used, such as link chains or belts, are also quite thin, so their elongations and accordingly the difference of elongation may become large enough to cause problems. For example, if the drive elements used in a 100 m long conveyor are link chains with a pitch of ⅝″, then the elongation of the link chain may be as much as about 30 cm. The difference of elongation of the link chains used as first and second drive elements may be e.g. about 10 cm. The difference of elongation becomes the more pronounced the longer and thinner the chains are.
The difference of elongation may be due to different tolerances of the chains and/or different wear resulting from uneven loading of the conveyor. Uneven loading again may be due to the fact that passengers usually stand on the right-hand side of the conveyor. Therefore, the drive element on the right-hand side undergoes greater elongation than does the drive element on the left-hand side.
In prior art, as the diverting pulleys at the non-driven end of the conveyor are in no way synchronized with each other and because the transport platforms are fastened to both drive elements, the difference of elongation accumulating at the non-driven end of the conveyor leads to a problematic situation where the transport platforms especially near the non-driven end of the conveyor tend to move in a position differing from the mutually parallel position at the driven end, that is to say, in an oblique position relative to the transport direction, which may result in the transport platforms being stuck on their guide rails, thus stopping the conveyor.